Winding coils are incorporated into a wide variety of products, for example, into inductors and transformers. More particularly, in electrical power transmission systems, various components, for example, a power transformer or a shunt reactor, can include one or more winding coils. Various types of faults can occur in these windings when in use. Some of these faults, for example, a short circuit between the output terminals of a power transformer are more readily detectable than other faults such as, an internal short circuit between a few turns of a primary winding or a secondary winding of the power transformer. The internal short circuit between the few turns may not necessarily result in a significant change in the amount of current being delivered by the power transformer to a power transmission line that is coupled to the power transformer. However, if timely remedial action is not taken, such a fault can eventually develop into a major fault that can severely impact power transmission through the power transmission line.
Conventional fault detection devices which are typically configured to detect significant current changes in various types of windings may be unable to effectively detect small turn-to-turn faults in such windings. More particularly, conventional fault detection devices may lack adequate sensitivity to detect changes in low amplitude differential currents that are indicative of turn-to-turn faults. Consequently, some solutions have been proposed that are directed at detecting turn-to-turn faults using other techniques. For example, one conventional solution generally pertains to fault detection in a power transformer or power line by using various phase current measurements to identify a source of negative sequence differential current, wherein such a source is indicative of a fault. Another conventional example generally pertains to a negative sequence differential element that is used to detect a fault in an electrical power system by computing a differential between negative sequence values derived from a first phase-current measurement and a second phase-current measurement.
Conventional solutions using negative sequence differential currents for fault detection can be impacted by various system imbalance conditions that can impact the sensitivity and the reliability of the detection process. Further, even when a fault is detected, the precise location of the fault in terms of a particular phase in a multi-phase system may not be identifiable.